The experimenter who does not know what he is looking for will not understand what he finds.

It is what we know already that often prevents us from learning.

The true worth of an experimenter consists in his pursuing not only what he seeks in his experiment, but also what he did not seek.

Mediocre men often have the most acquired knowledge.

Art is I; science is we.

Man can learn nothing except by going from the known to the unknown.

Observation is a passive science, experimentation an active science.

Put off your imagination, as you put off your overcoat, when you enter the laboratory. Put it on again, as you put on your overcoat, when you leave.

The investigator should have a robust faith – and yet not believe.

The experimenter who does not know what he is looking for will not understand what he finds.

Experimentation is an active science.

A fact in itself is nothing. It is valuable only for the idea attached to it, or for the proof which it furnishes.

In teaching man, experimental science results in lessening his pride more and more by proving to him every day that primary causes, like the objective reality of things, will be hidden from him forever and that he can only know relations.

Science does not permit exceptions.